Field of the Invention
The present invention relates to a jig which can hold a pillar-like body without causing damage to the pillar-like body, even when the pillar-like body has an irregular shape, a poor shape accuracy, and brittleness, and relates to a device which measures a pressure loss of the pillar-like body held by the jig.
Description of Related Art
As a loading body onto which a catalyst to purify an exhaust gas of an automobile is loaded, a honeycomb structure is often used. This honeycomb structure is also broadly used as a particulate filter (PF) which collects and removes a particulate matter (PM) included in the exhaust gas. Moreover, examples of the PF include a DPF for a diesel engine and a GPF for a gasoline engine.
In general, the honeycomb structure is a brittle ceramic product, and an outer shape of the honeycomb structure is columnar in many cases. In the honeycomb structure, a plurality of cells are arranged so as to communicate between two end surfaces of the columnar body. The cells are formed by a plurality of partition walls, and the partition walls are porous walls having a large number of pores. Moreover, when the honeycomb structure is used as the PF, (exhaust gas) inflow end surfaces of predetermined cells and (exhaust gas) outflow end surfaces of the remaining cells are alternately plugged. When the honeycomb structure is used as the PF, the exhaust gas which has flowed into the cells from an inflow end surface side is discharged from an outflow end surface side through the partition walls which function as filter layers. At this time, the particulate matter in the exhaust gas is trapped on the porous partition walls.
The catalyst or filter using such a honeycomb structure is usually disposed in through channels of the exhaust gas (e.g., exhaust tubes of the automobile). Therefore, when the exhaust gas passes through the honeycomb structure, a resistance takes place and has an influence on a performance of the engine. In consequence, as one of specifications of the catalyst or the filter, a pressure loss at a predetermined flow rate is requested to be provided.
From such situations, there arises a necessity of measuring the pressure loss of the honeycomb structure which is the catalyst loading body or filter itself. Moreover, in the measurement of the pressure loss, it is necessary to firmly hold and fix the honeycomb structure which is a measurement object so that the honeycomb structure does not become unstable during the measurement even when the exhaust gas for the measurement is allowed to flow at the predetermined flow rate. Heretofore, the measurement of the pressure loss and the holding of the honeycomb structure for the measurement have been performed by means (conventional art) disclosed, for example, in Patent Documents 1 to 3.
In recent years, however, as the honeycomb structures, integrally formed products have increased in which an outer shape is pillar-like but is not columnar (a cross section perpendicular to a central axis is not round) and the cross section has an irregular shape. In the honeycomb structures having such an irregular shape, a shape (a dimension) varies sometimes as much as about ±10 mm or more from a design value which is a reference. This is because the honeycomb structure is manufactured through a firing process of a ceramic material. In particular, when the cross section is elliptic, a deviation concerning perpendicularity or torsion (circumferential deflection) easily increases. Moreover, the integrally formed product is not subjected to shape correction processing, and hence in the above conventional technology, it is difficult to hold the honeycomb structure having a poor shape accuracy and to accurately measure the pressure loss sometimes. A reason for this case is that at the measurement of the pressure loss, it is necessary to hold the honeycomb structure in such an airtight state that a total amount of the exhaust gas for the measurement passes through the honeycomb structure without any leakage, but in the conventional technology, the honeycomb structure having the varying shape accuracy cannot be held with an excellent air tightness. In the conventional technology, a limit of a shape tolerance of the honeycomb structure to be held (a difference between a maximum value and a minimum value of an allowable dimension) has been about ±2 mm when the cross section is round, and about ±1 mm when the cross section has the irregular shape.